iOS 8.3 (build 12F70) is an official Apple over-the-air update for the iPhone 4s, released on 2015-04-08T17:56:09Z. The update package is 313.48 MB. This is a delta (partial) update that requires 8.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: cac8eb6ad721d9e1ec0a0afa2f27721815f7e7fe.zip.